Field Guide · technology

Also known as: Meshtastic

Meshtastic is an open-source project that turns cheap LoRa radio modules into an off-grid mesh for short text messages and GPS positions, with no carrier, gateway, or internet required.1 Each low-cost node (typically an ESP32 or nRF52 board with a LoRa transceiver) both originates messages and relays its neighbors’, so a handful of devices extends communication for kilometres across terrain where phones have no signal — hiking, sailing, events, and emergency scenarios.

A B C D E a message hops node-to-node — no gateway, no cell tower
Meshtastic relays messages hop-by-hop across peer nodes over LoRa; there is no central gateway, unlike LoRaWAN.

How it works

Meshtastic sits directly on the LoRa physical layer but is not LoRaWAN: it needs no gateway or network server. Instead it uses managed flooding — when a node receives a packet it has not seen, it rebroadcasts it, with hop limits and rebroadcast suppression to keep the flood from exploding. Nodes share a channel defined by a name and a pre-shared AES key, so members of the same channel see each other’s traffic while it stays private to outsiders.

Because it rides on LoRa’s chirp modulation, Meshtastic inherits long range at very low power and low data rate. Devices expose a phone app over Bluetooth or Wi-Fi for composing messages, viewing the map of nodes, and configuring channels, while the radio itself keeps running on a small battery or solar for days.

Key design points:

  • Decentralized — every node is a router; there is no infrastructure to deploy.
  • Preset “modem” profiles trade range against speed by selecting LoRa spreading factor and bandwidth (e.g. “Long Fast” vs “Short Fast”).
  • Encrypted channels — AES protects payloads on a shared-key basis, not per-device cellular-style authentication.

Relevance to SDR

Meshtastic traffic is ordinary LoRa on sub-GHz ISM bands, so on an SDR waterfall it looks like LoRa’s characteristic diagonal chirps in the 433/868/915 MHz frequency bands. A general software-defined radio plus a LoRa demodulator can detect and, with the channel key, decode packets — but this is squarely outside GopherTrunk, which decodes trunked land-mobile voice (P25, DMR, NXDN, TETRA, …) and implements neither the LoRa PHY nor the Meshtastic mesh protocol. Meshtastic is included here as context for the sub-GHz IoT signals a scanner operator will encounter on the band.

Sources

  1. Meshtastic — Wikipedia, for the open-source LoRa mesh design, managed flooding, and off-grid use. ↩

See also